Inlet orifice of blower fan of fan coil unit

ABSTRACT

A blower fan of a fan coil unit includes a fan wheel including a first end ring, a second end ring, and a plurality of blades that extend between the first end ring and the second end ring. The plurality of blades define a wheel inner diameter, and each of the first end ring and the second end ring define an end ring inner diameter. The blower fan also includes a housing including an inlet orifice having an orifice diameter. The fan wheel is located within the housing. The orifice diameter is substantially equal to the end ring inner diameter and greater than the wheel inner diameter.

REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Application No.61/039,513 filed Mar. 26, 2008.

BACKGROUND OF THE INVENTION

This invention relates generally to a blower fan of a fan coil unitincluding a housing having an inlet orifice with a diameter that issubstantially equal to an inner diameter of an end ring of a fan wheelreceived in the housing.

A fan coil unit includes a blower fan and a coil. Refrigerant flowsthrough the coil, and the blower fan draws air over the coil. Heat isexchanged between the air drawn over the coil and the refrigerantflowing through the coil.

One example blower fan includes a fan wheel located in a housing. Thefan wheel includes a plurality of blades that extend between two endrings and that define an inner diameter and an outer diameter of the fanwheel. The housing includes an inlet orifice having an orifice diameter,and air is drawn into the housing through the inlet orifice. In oneexample, the diameter of the inlet orifice is approximately equal to theinner diameter of fan wheel. Therefore, the housing covers the ends ofthe blades, hindering the flow of the air entering the blades.

Another example blower fan includes a fan wheel including a plurality ofblades that extend between an end ring and an endplate. The end ring hasan inner diameter that defines a central opening. The endplate includesa hub that receives a shaft. The endplate is only defined by the outerdiameter and does not have an inner diameter that defines a centralopening once the shaft is received in the hub.

SUMMARY OF THE INVENTION

A blower fan of a fan coil unit includes a fan wheel including a firstend ring, a second end ring, and a plurality of blades that extendbetween the first end ring and the second end ring. The plurality ofblades define a wheel inner diameter, and each of the first end ring andthe second end ring define an end ring inner diameter. The blower fanalso includes a housing including an inlet orifice having an orificediameter. The fan wheel is located within the housing. The orificediameter is substantially equal to the end ring inner diameter andgreater than the wheel inner diameter.

Another aspect provides a fan coil unit including a coil through whichrefrigerant flows and a blower fan that draws air over the coil. Theblower fan includes a first end ring, a second end ring, and a pluralityof blades that extend between the first end ring and the second endring. The plurality of blades define a wheel inner diameter, and each ofthe first end ring and the second end ring define an end ring innerdiameter. The blower fan also includes a housing including an inletorifice having an orifice diameter. The fan wheel is located within thehousing. The orifice diameter is substantially equal to the end ringinner diameter and greater than the wheel inner diameter.

Another aspect provides a refrigeration system including a compressorfor compressing a refrigerant, a condenser for cooling the refrigerant,an expansion device for expanding the refrigerant, and a fan coil unitincluding an evaporator coil and a blower fan. The refrigerant flowsthrough the evaporator coil, and the blower fan draws air over theevaporator coil to reject heat to the refrigerant. The blower fanincludes a first end ring, a second end ring, and a plurality of bladesthat extend between the first end ring and the second end ring. Theplurality of blades define a wheel inner diameter, and each of the firstend ring and the second end ring define an end ring inner diameter. Theblower fan also includes a housing including an inlet orifice having anorifice diameter. The fan wheel is located within the housing. Theorifice diameter is substantially equal to the end ring inner diameterand greater than the wheel inner diameter.

These and other features of the present invention will be bestunderstood from the following specification and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The various features and advantages of the invention will becomeapparent to those skilled in the art from the following detaileddescription of the currently preferred embodiment. The drawings thataccompany the detailed description can be briefly described as follows:

FIG. 1A illustrates a refrigeration system operating in a cooling cycleincluding a fan coil unit;

FIG. 1B illustrates a refrigeration system operating in a heating cycleincluding the fan coil unit;

FIG. 2 illustrates an example fan coil unit;

FIG. 3 illustrates a perspective view of a blower fan of the fan coilunit including a housing and a fan wheel;

FIG. 4 illustrates a perspective view of an enlarged view of a portionof the blower fan of FIG. 3; and

FIG. 5 illustrates a perspective view of the fan wheel of the blowerfan.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1A illustrates a refrigeration system 20 operating in a coolingmode. Refrigerant flows through the closed circuit refrigeration system20. The refrigeration system 20 includes a fan coil unit 21 locatedinside 17 a building and an outdoor unit 23 located outside 15 thebuilding. The inside 17 of the building and the outside 15 of thebuilding can be separated by a wall 19.

Refrigerant exits a compressor 22 in the outdoor unit 23 at a highpressure and a high enthalpy. A reversing valve 25 directs therefrigerant through a first heat exchanger 24, which operates as acondenser. In the first heat exchanger 24, the refrigerant flows througha coil 26 and rejects heat to air that is drawn over the coil 26 by afan 29. In one example, the fan 29 is a propeller fan. In the first heatexchanger 24, the refrigerant is condensed into a liquid that exits thefirst heat exchanger 24 at a low enthalpy and a high pressure.

The refrigerant bypasses an outdoor expansion device 26 b (describedbelow) and travels to the fan coil unit 21 through tubing 37. In the fancoil unit 21, the cooled refrigerant then passes through an indoorexpansion device 26 a, expanding the refrigerant to a low pressure.After expansion, the refrigerant flows through a second heat exchanger28, which operates as an evaporator. A blower fan 30 draws air throughthe second heat exchanger 28 and over a coil 27. The refrigerant flowingthrough the coil 27 accepts heat from air, exiting the second heatexchanger 28 at a high enthalpy and a low pressure.

The refrigerant then flows back to the outdoor unit 23 through tubing39. The refrigerant can flow through an accumulator 31, which regulatesthe amount of refrigerant flowing through the refrigeration system 20.The refrigerant then flows to the compressor 22, completing the cycle.

FIG. 1B illustrates the refrigeration system 20 operating in a heatingmode. Refrigerant exits the compressor 22 in the outdoor unit 23 at ahigh pressure and a high enthalpy. The reversing valve 25 directs therefrigerant to the fan coil unit 21 through the tubing 39.

In the fan coil unit 21, the refrigerant flows through the second heatexchanger 28, which operates as a condenser. A blower fan 30 draws airthrough the second heat exchanger 28 and over the coil 27. In the secondheat exchanger 28, the refrigerant flows through the coil 27 and rejectsheat to air and is condensed into a liquid, exiting the second heatexchanger 28 at a low enthalpy and a high pressure. The refrigerantexits the coil 27 and bypasses the indoor expansion device 26 a.

The refrigerant exits the fan coil unit 21 and flows through the tubing37 towards the outdoor unit 23, where the refrigerant is expanded to alow pressure in the outdoor expansion device 26 b. After expansion, therefrigerant flows through the first heat exchanger 24, which operates asan evaporator. In the first heat exchanger 24, the refrigerant flowsthrough the coil 26 and accepts heat from air that is drawn over thecoil 26 by the fan 29, exiting the first heat exchanger 24 at a highenthalpy and a low pressure. The refrigerant can flow through theaccumulator 31. The refrigerant then flows to the compressor 22,completing the cycle.

FIG. 2 illustrates the fan coil unit 21. The fan coil unit 21 includes ahousing 41 that contains the blower fan 30 that draws the air over thecoil 26. A motor 58 rotates the blower fan 30 about an axis of rotation70. Air enters the blower fan 30 through an inlet orifice 60 and exitsthe blower fan 30 through an outlet 68.

As shown in FIGS. 3 and 4, the blower fan 30 includes a fan wheel 32 anda housing 34. In one example, the housing 34 is metal. The fan wheel 32rotates about the axis of rotation 70. As further shown in FIG. 5, thefan wheel 32 includes a first end ring 36 and a second end ring 38. Theend rings 36 and 38 are substantially the same size and shape. In oneexample, the end rings 36 and 38 are substantially circular in shape.The end rings 36 and 38 define an end ring inner diameter 66.

The fan wheel 32 also includes a plurality of blades 40 each having afirst end 42 and a second end 44. The plurality of blades 40 are equallyspaced and define a space 46 between each of the plurality of blades 40.The plurality of blades 40 are substantially parallel to each other andsubstantially perpendicular to the end rings 36 and 38. The plurality ofblades 40 define a wheel inner diameter 64.

The ends 42 and 44 of the blades 40 are each connected to a base portion(not shown), and each of the end rings 36 and 38 are attached to one ofthe base portions. In one example, the end rings 36 and 38 are attachedto the base portions by crimping. In one example, the fan wheel 32 issubstantially cylindrical in shape. A cross-section of each of theplurality of blades 40 taken substantially perpendicularly to a length48 of the blades 40 is substantially arc-shaped.

A wheel disc 50 is attached to the plurality of blades 40 at a location52 along the length 48 of the blades 40 that is substantiallyequidistant from each of the ends 42 and 44. The wheel disc 50 includesa hub 51 that receives a shaft 54 of the motor 58, and a setup screw 53mounts the wheel disc 50 to the shaft 54. As the motor 58 rotates theshaft 54, the fan wheel 32 rotates about the axis of rotation 70 to drawair into the fan wheel 32.

The housing 34 includes the inlet orifice 60 and the outlet 68. In oneexample, the inlet orifice 60 is substantially circular and has anorifice diameter 62. The fan wheel 32 is installed in the housing 34such that the axis of rotation 70 of the fan wheel 32 is substantiallycentered within the inlet orifice 60. In one example, the housing 34includes a planar surface 61, and the inlet orifice 60 is defined in theplane of the planar surface 61.

As the fan wheel 32 rotates about the axis of rotation 70, air is drawninto the inlet orifice 60 of the housing 34 and through the spaces 46between the blades 40 of the fan wheel 32. The air is directed in anoutwardly direction relative to the axis of rotation 70 of the fan wheel32 and through the outlet 68 of the housing 34. The blower fan 30 drawsair over the coil 27, the air exchanging heat with the refrigerantflowing through the coil 27.

As stated above, the second heat exchanger 28 can be an evaporator or acondenser. If the second heat exchanger 28 is an evaporator, the airrejects heat to the refrigerant flowing through the coil 27. If thesecond heat exchanger 28 is a condenser, the air accepts heat from therefrigerant flowing through the coil 27.

The size and shape of the inlet orifice 60 affects the flow of air intothe fan wheel 32, and therefore efficiency. The orifice diameter 62 ofthe inlet orifice 60 of the housing 34 is approximately equal to orgreater than the end ring inner diameter 66 of the end rings 36 and 38of the fan wheel 32. The orifice diameter 62 of the inlet orifice 60 istherefore greater than the wheel inner diameter 64 (defined by theinnermost portion of the blades 40), and the ends 42 and 44 of theblades 40 are partially exposed by the housing 34. In another example,the ends 42 and 44 of the blades 40 are entirely exposed by the housing34. The air can be directly drawn into the fan wheel 32, and therotation of the fan wheel 32 helps the air evenly flow over the fanwheel 32. The air is not required to make abrupt turns from the inletorifice 60 to blade regions near the ends 42 and 44 of the blades 40,which could impede the flow in the region near the ends 42 and 44 of theblades 40.

In prior fan wheels, the orifice diameter of the inlet orifice isapproximately equal the wheel inner diameter defined by the innermostportion of the blades. Therefore, a portion of the housing covers theends of the blades, and this portion prevents the direct passage of airinto the fan wheel. The air must make an abrupt turn around this portionof the housing to enter the fan wheel, reducing efficiency.

The size and shape of the inlet orifice 60 of the housing 34 isoptimized to affect the flow of air drawn into the fan wheel 32 andimprove the efficiency of the blower fan 30. By optimized, it is meantthat the orifice diameter 62 of the inlet orifice 60 of the blower fan30 is enlarged such that the orifice diameter 62 is substantially equalto the end ring inner diameter 66 of the end rings 36 and 38, partiallyexposing the ends 42 and 44 of the plurality of blades 40. Additionally,in one example, the inlet orifice 60 can be substantially circular tocorrespond to the shape of the fan wheel 32.

In one example, for a 42 size fan coil unit, enlarging the orificediameter 62 of the inlet orifice 60 such that the orifice diameter 62 isapproximately equal to the inner diameter 66 of the end rings 36 and 38reduces the power of the blower fan 30 by approximately 6% at the sameoperation point (same airflow and same external static pressure) as ablower fan of the prior art, saving costs. The aerodynamic flow of theblower fan 30 reduces the watts consumption of the blower fan 30,reducing the cost of the outdoor unit 23. The size of the blower fan 30could also be reduced.

The foregoing description is only exemplary of the principles of theinvention. Many modifications and variations of the present inventionare possible in light of the above teachings. The preferred embodimentsof this invention have been disclosed, however, so that one of ordinaryskill in the art would recognize that certain modifications would comewithin the scope of this invention. It is, therefore, to be understoodthat within the scope of the appended claims, the invention may bepracticed otherwise than as specifically described. For that reason thefollowing claims should be studied to determine the true scope andcontent of this invention.

1. A blower fan of a fan coil unit, the blower fan comprising: a fanwheel including a first end ring, a second end ring, and a plurality ofblades that extend between the first end ring and the second end ring,wherein the plurality of blades define a wheel inner diameter and eachof the first end ring and the second end ring define an end ring innerdiameter; and a housing including an inlet orifice having an orificediameter, wherein the fan wheel is located within the housing and theorifice diameter is substantially equal to the end ring inner diameterand greater than the wheel inner diameter.
 2. The blower fan as recitedin claim 1 wherein each of the plurality of blades has a length, and across-section of each of the plurality of blades taken substantiallyperpendicularly to the length is substantially arc-shaped.
 3. The blowerfan as recited in claim 1 wherein a space is defined between each of theplurality of blades, and each of the spaces is approximately equal. 4.The blower fan as recited in claim 1 further including a wheel discattached to each of the plurality of blades at a location that issubstantially equidistant from a first end and an opposing second end ofthe plurality of blades.
 5. The blower fan as recited in claim 4 whereinthe wheel disc includes a hub that receives a shaft of a motor, and themotor rotates the shaft to rotate the fan wheel about an axis ofrotation.
 6. The blower fan as recited in claim 1 wherein a first endand an opposing second end of each of the plurality of blades ispartially exposed by the inlet orifice and uncovered by the housing. 7.The blower fan as recited in claim 1 wherein the fan wheel draws airover a coil of a heat exchanger and into the inlet orifice of thehousing and discharges the air through an outlet of the housing.
 8. Theblower fan as recited in claim 1 wherein the plurality of blades aresubstantially parallel.
 9. The blower fan as recited in claim 1 whereinthe fan wheel is substantially cylindrical.
 10. A fan coil unitcomprising: a coil, wherein refrigerant flows through the coil; and ablower fan that draws air over the coil to exchange heat with therefrigerant flowing through the coil, wherein the blower fan includes afan wheel including a first end ring, a second end ring, and a pluralityof blades that extend between the first end ring and the second endring, wherein the plurality of blades define a wheel inner diameter andeach of the first end ring and the second end ring define an end ringinner diameter, and the blower fan includes a housing including an inletorifice having an orifice diameter and an outlet, wherein the fan wheelis located within the housing to draw the air over the coil and into theinlet orifice and discharge the air through the outlet, and the orificediameter is substantially equal to the end ring inner diameter andgreater than the wheel inner diameter.
 11. The fan coil unit as recitedin claim 10 wherein each of the plurality of blades has a length, and across-section of each of the plurality of blades taken substantiallyperpendicularly to the length is substantially arc-shaped.
 12. The fancoil unit as recited in claim 10 wherein a space is defined between eachof the plurality of blades, and each of the spaces is approximatelyequal.
 13. The fan coil unit as recited in claim 10 further including awheel disc attached to each of the plurality of blades at a locationthat is substantially equidistant from the first end and the opposingsecond end of the plurality of blades.
 14. The fan coil unit as recitedin claim 13 wherein the wheel disc includes a hub that receives a shaftof a motor, and the motor rotates the shaft to rotate the fan wheelabout an axis of rotation.
 15. The fan coil unit as recited in claim 10wherein a first end and an opposing second end of each of the pluralityof blades is partially exposed by the inlet orifice and uncovered by thehousing.
 16. The fan coil unit as recited in claim 10 wherein theplurality of blades are substantially parallel.
 17. The fan coil unit asrecited in claim 10 wherein the fan wheel is substantially cylindrical.18. A refrigeration system comprising: a compressor for compressing arefrigerant; a condenser for cooling the refrigerant; an expansiondevice for expanding the refrigerant; and a fan coil unit including anevaporator coil and a blower fan, wherein the refrigerant flows throughthe evaporator coil and the blower fan draws air over the evaporatorcoil to reject heat to the refrigerant, wherein the blower fan includesa fan wheel including a first end ring, a second end ring, and aplurality of blades that extend between the first end ring and thesecond end ring, the plurality of blades define a wheel inner diameterand each of the first end ring and the second end ring define an endring inner diameter, and the blower fan includes a housing including aninlet orifice having an orifice diameter and an outlet, and wherein thefan wheel is located within the housing to draw the air over theevaporator coil and into the inlet orifice and discharge the air throughthe outlet, and the orifice diameter is substantially equal to the endring inner diameter and greater than the wheel inner diameter.